The group behind the poll painted a gloomy picture for the Bay Area's future.

"Losing our youth is a very bad economic and social strategy," Jim Wunderman, president and CEO of the Bay Area Council, said in a statement. "But until we get serious about building the housing we need we're going to continue seeing our region drained of the young and diverse talent that has helped make the Bay Area an economic powerhouse."

The Bay Area draws in millennials with its top-ranked colleges, vibrant culture, and proximity to Silicon Valley, where the promise for young entrepreneurs of becoming the next tech billionaire never dies. The region has added about 100,000 new jobs every year since 2011, though growth is starting to wane, and unemployment levels are at their lowest in 15 years.

Even still, millennials are struggling to make ends meet.

In 2013, millennials made up about 30% of San Francisco's population, according to US Census data.Gabrielle Lurie/Reuters

The Bay Area is one of the most competitive rental markets in the US. In San Francisco, the median rent tops $4,200 a month, according to real estate site Trulia.

These urban dwellers are finding creative — and sometimes uncomfortable — solutions to make it work. They live in sailboats, tiny houses, vans, and even wooden boxes of their own making. An increasing number of millennials are squeezing into apartments and homes with large numbers of people. Communal living, or "co-living," is often more affordable than traditional rentals because it comes with perks, like free internet, maid service, and new friends.

The results of the Bay Area Council's poll shows millennials may no longer see a future there.

Wunderman, of the Bay Area Council, told The San Francisco Business Times that young people flocked to the Bay Area after graduating college or completing graduate programs. Now that those transplants are entering their 30s, they're thinking about starting a family or owning a home. It's less and less doable as the housing affordability crisis continues.

"I would say the thinking amongst younger folks that the Bay Area doesn't hold their future is really settling in and that's concerning," Wunderman said.

About SaveMarinwood.org

Our community is what we make it. Marinwood-Lucas Valley is on the eve of a fateful decision by the Marin County Board of Supervisors to designate our community with 71% of all affordable housing in unincorporated Marin. If built to plan it will swell our community by 25% and add 600-1000 school children to the Dixie School District. Since affordable housing developments pay virtually no taxes, the community will have to pay for the $6 million to $10 million annually estimated to educate these children. Our total budget for the Marinwood CSD is $4.2 million dollars. Clearly it will have a severe impact on our community.

We support a fair allocation of affordable housing in our community that is sensitive to land use, is fiscally responsible, healthy for the families and integrates diversity within our community.

Unfortunately, planners, politicians and political insiders made their plans without us.